Virus is the cause of various disorders. For example, members of the coronavirus family cause hepatitis in mice, gastroenteritis in pigs, and respiratory infections in birds and humans. Among the more than 30 strains isolated so far, three or four infect humans. The severe acute respiratory syndrome (SARS), a newly found infectious disease, is associated with a novel coronavirus. This life-threatening respiratory coronavirus has touched off worldwide outbreaks in 2003. Vaccines and drugs against SARS coronavirus are vigorously sought. Nevertheless, the progress is rather slow due to safety concerns.
Baculoviruses, a group of insect-borne viruses, are safe for use in humans. They have been successfully used for generating active engineered protein in some mammalian cells. See, e.g., King et al., The Baculovirus Expression System: A Laboratory Guide; Chapman and Hall: London, 1992; Luckow, Curr. Opin. Biotechnol. 1993, 4, 564-572; O'reilly, et al., Baculovirus Expression Vectors: A Laboratory Manual, Oxford University Press: New York, 1994; and Smith et al., 1983, Mol. Cell Biol. 3, 2156-2165. On the other hand, as baculoviruses are quite different from coronaviruses and do not efficiently infect coronavirus target cells, their use in developing anti-coronavirus agents has been limited.